1. Field of the Invention
The present invention relates to signal detection and, more particularly, to detection of a spread spectrum signal and determination of its spreading sequence.
2. Brief Description of Related Developments
Wireless communications systems are commonly employed to provide voice and data communications to users. Such communications systems may use spread spectrum modulation where a data modulated carrier is modulated by a spreading sequence before being transmitted. The spreading sequence usually includes a pseudo-random number (PN) sequence occurring at a chip rate much higher than the bit rate of the data sequence being transmitted.
In a typical spread spectrum receiver, the modulated signal is typically correlated with the particular spreading sequence to produce an estimate of the transmitted data sequence. However, in order to “despread” the spread spectrum signal, the receiver must have information related to the spreading sequence used to modulate the data sequence.
It would be advantageous to be able to detect a spread spectrum signal with unknown characteristics, for example, center frequency, chip rate, spreading sequence, etc., and to identify the spreading sequence of the detected signal for determination of the signal's data sequence.